1. Field of the Invention:
The present invention relates to an improved connecting means operable to shield cables and circuits from electromagnetic interference (EMI) in multi-shell connectors having electrical connector pins.
This device molds or bonds a highly electrically conductive rubber seal to at least one-half of the male or female portion of the multi-shell connector thereby closing any and all air gaps between the mated individual shells of the connectors. During connector engagement this conductive rubber seal provides a low surface impedance between the mated connector shells and an electromagnetic interference (EMI) shield is formed with no openings to the connector pins.
Another embodiment of invention incorporates an additional seal to the multi-shell connectors serving as an environmental shield providing physical protection for the eletrical connection pins from the outside environment during connector operation in adverse environments.
2. Description of the Prior Art:
The miniaturization of electronic equipment has created the need for connectors to electrically support that electronic equipment with a stable electrical signal input. To date, in the area of radio frequency and electromagnetic interference reduction, emphasis has been placed on protecting the miniaturized circuits from mutual radio frequency interference and electromagnetic interference (EMI).
It is well known in the prior art specifically applicable to the shielding of electrical devices and circuits; to shield individual circuits within electronic modules and complete electronic modules in and of themselves. Also, the interconnecting circuits for these modules have been protected by various shielding techniques which provide for low resistance, high permeability strength and flexibility.
The U.S. Pat. No. 4,519,664, issued May 28, 1985 to J. D. Tillotson, entitled, "Multipin Connector and Method of Reducing EMI by Use Thereof", discloses a multi-pin connector operable in the 5-30 MHz range. The individual pins of the Tillotson connector are electrically isolated one from the other by a material having a high magnetic permeability, and a low magnetic retention. And, a second electronically conductive material surrounds the pins. Use of the Tillotson connector results in radiated EMI from the electrical harness dissipated in the form of heat energy within the material surrounding each pin.
The U.S. Pat. No. 3,617,607, issued Nov. 2, 1971 to J. D. Williams, entitled, "Electromagnetic Interference Shield Isolator", discloses a coupler ring operable to isolate and shield cables utilizing an insulating shell for the cable connector housing.
Finally, the U.S. Pat. No. 2,379,942, issued July 10, 1945 to C. A. Webber, entitled, "Cable Terminating Means", describes a cable terminating apparatus for electrical connectors connecting flexible high potential cables. The Webber connector prevents the breakdown of the insulation in connecting cables as a result of a corona discharge through entrapped air pockets, thereby forming ozone. The "shield" in the Webber connector U.S. Pat. No. 2,379,942 comprises a stranded conductor surrounded by; first a thin layer of conducting material, second a thick layer of insulating rubber, and thirdly a thin layer of conducting rubber.
While the various connectors as taught by the prior art addresses various types of EMI shielding needs; none of the prior art patents described above disclose an EMI shield for miniature "D" style connectors. Specifically, no art was found disclosing a seal or ring operable to fill the air gap between mated connectors thereby minimizing EMI leakage of electrical signals as between multi-shell connectors.
The EMI seal described as the preferred embodiment of this application is a highly conductive rubber seal operable to provide low surface impedance between the multi-shells of the connector without external contact of the connecting pins.
The "missing link" in the prior art EMI shielding "chain" is the lack of shielding for the interconnection of cables between miniature electronic devices. Specifically, the problem to be solved is the effective EMI shielding of cables using D style connectors.